The invention relates to a joining means having a ram tool and a countertool, and a holder having an opening to accommodate the ram tool or the countertool. The two tools are oriented coaxial with each other at different ends of a C-bracket.
Such joining means are known and serve in particular to produce connections, for example rivet and self-piercing rivet connections. Known joining means comprise a ram provided with a drive and, as countertool, a matching die, arranged coaxial with each other, exacting requirements being imposed on the coaxiality of ram and die, since the strength and appearance of the connection produced depend on this to a very large extent. The coaxiality must be ensured for the long term and with the joining means in motion, since a large number of connections per unit time are produced by these means with the aid of robots. The so-called C-frame or C-bracket here serves as suspension and abutment in the motion of the tool, the C-bracket in the first place exhibiting low mass, and in the second place intended to assume the forces that occur in the process of connection. Similar problems arise in pressing, embossing machines and punches, i.e. wherever two cooperating tools (ram and die or anvil) must be oriented coaxially with each other.
The printed source DE 197 43 277 A1 describes a joining means of the kind mentioned in which, in a receiving bore in the upper web of a C-bracket, two eccentric sleeves are arranged for suspension of a rivet-setting tool. The eccentric sleeves comprise like eccentricity and are rotated relative to each other with a hook wrench to adjust the coaxiality or equalize faults of alignment. The rotary position can be fixed by means of a screw insertable in recesses on the periphery of the eccentric sleeve. The article “Stanznieten ist zukunftsträchtig in der Blechverarbeitung” [Self-piercing riveting has a future in the working of sheet metal] in the periodical Bänder, Bleche, Rohre (No. 5 of [19]91), pages 94 ff., describes a known self-piercing rivet system in which the ram tool is bolted to the upper end of a C-bracket.
The object of the invention is to create a joining means whose coaxial setting of ram tool and countertool is simply and economically attainable. Here it must be ensured that the coaxiality is maintained in the long term and with the joining means in motion. This object is accomplished according to the invention by the joining means having the features according to Claim 1.
Apart from those advantages of the invention which correspond to the objective of achieving an economical, simple and enduring coaxiality of ram tool and countertool, it is made possible in addition by the joining means according to the invention to realize with a C-bracket the various tool distances and the use of various tools in various materials as well as the use of tool holders with different diameter of the receiving bore. Besides, the tools, in case of wear or further development, can be more simply, more quickly and more economically retrofitted or adapted to new problems. This is especially advantageous because C-brackets are very costly. They are made in one piece with the holder as a rule, because of the exacting requirements on rigidity. By separate fabrication from two or more parts, the production of the complete C-bracket can be rendered less expensive, and the C-bracket production time is shortened.
The objects described in the dependent claims represent advantageous refinements of the subject of Claim 1. It is advantageous in particular to make the interlayer wedge-shaped, since the axial position of the ram or countertool can be influenced in a particular direction. It is likewise of advantage to provide several contact surfaces at right angles to each other or formed by the inner surfaces of a U-shaped element, so that the tool is more stably configured in motion. A highly advantageous manifold serviceability of the holder with respect to the distance from the countertool is made possible if the holder and the corresponding end of the C-bracket are of such configuration that the holder is rotatable through 180°. Other advantages of the preferred embodiments will be found in the following description.